Downham Market in the context of "Market towns"

A market town is a settlement (commonly in Europe) that obtained a market right (by custom or royal charter) in the Middle Ages, which allowed it to host a regular market; this distinguished it from a village or a city. In Britain, small rural towns with a hinterland of villages are still commonly called market towns, and is sometimes reflected in their names (e.g. Downham Market, Market Rasen, or Market Drayton).

Modern markets are often in special halls, but this is a relatively recent development. Historically the markets were open-air, held in what is usually called (regardless of its actual shape) the market square or market place, sometimes centred on a market cross (mercat cross in Scotland). They were and are typically open one or two days a week. In the modern era, the rise of permanent retail establishments reduced the need for periodic markets.